A rechargeable battery, such as a lead-acid battery or a lithium-ion battery, has a limit for how much current it should be charged with. During charging the battery reacts by becoming warmer. High temperatures should be avoided since it may be harmful to the battery. In extreme cases the battery may explode or break down. If the battery can be prevented from becoming too warm, the expected lifetime of the battery can be prolonged.
A protection circuit that is adapted to disconnect a battery when the surface temperature of a battery rises over a given temperature is disclosed in the U.S. Pat. No. 5,608,304.
There are also other conditions apart from high temperature states during which a high charge current may impact the battery negatively. Some batteries have a current limit that depends on its State of Charge (SOC) or previous charge history.
At the same time as it is desired to prevent the battery from becoming too warm or harmed due to some other type of condition it is also desirable to achieve fast and efficient charging of the battery. There is therefore a need for methods and apparatuses that achieve a good balance between these two competing interests.